Category: Fiber Tester & Tools

Fiber optic testers, fiber optic tools, fiber splicing, fiber polishing, copper testers and tools.

Overview of 100G QSFP28 Optical Transceivers

by http://www.fiber-mart.com

QSFP28 fiber optic module has become the dominant form factor for 100G high-speed networks. The interconnect offers multiple channels of high-speed differential signals with data rates ranging from 25Gbps up to potentially 40Gbps, and meets 100Gbps Ethernet (4×25Gbps) and 100Gbps 4X InfiniBand Enhanced Data Rate (EDR) requirements. Fiber-mart 100G QSFP28 optical transceiver including SR4, LR4, PSM4, CWDM4 and AOCs, complied with IEEE 802.3bm and SFF-8636, compatible with network device from different vendors, designed for applications of 100G Data Center Internal Network, Data Center Interconnection and Metro Network.
The following list is QSFP28 fiber optic transceivers form Fiber-mart.com, it is able to compatible with the main network device provider like Cisco, HPE, Huawei, etc.
QSFP28 SR4: The QSFP28-SR4 optical module supports links of 70m over OM3 MMF and 100m over OM4 MMF with MPO-12 or MTP-12 connectors. This transceiver is a parallel 100G QSFP28 optical module with 4 independent transmit and receive channels each capable of 25Gb/s operation. The 100G QSFP28-SR4 modules are ideal for rack to rack connections in the datacenter and short reach telecom applications.The QSFP28-100G-eSR4 is extended version of QSFP for transmit over 300m.
QSFP28 PSM4: The 100G PSM4 specification defines requirements for a point-to-point 100 Gbps link over eight single mode fibers (4 transmit and 4 receive) of at least 500m, each transmitting at 25Gbps. Four identical and independent lanes are used for each signal direction. PSM4 does not need a MUX/DEMUX for each laser but it does need either a directly modulated DFB laser (DML) or an external modulator for each fiber. With an MTP interface, PSM4 modules can bus 100Gbps point-to-point over 2km or can be broken out into dual 50Gbps or quad 25Gbps links for linking to servers, storage and other subsystems.
QSFP28 CWDM4: The CWDM4 module uses Mux/Demux technologies with 4 lanes of 25 Gbps optically multiplexed onto and demultiplexed from duplex single-mode fiber. It is centered around the 1310nm band with 20nm channel spacing as defined by the ITU standard. With a reach of 2km, QSFP28 CWDM4 transmits 100G optical signals via a duplex LC interface.
QSFP28 LR4: This module is for longer span 100GbE deployment, such as connectivity between two buildings, QSFP28-LR4 with duplex LC fiber interface and transmitted over single-mode fiber cable. This LR4 module uses WDM technologies to achieve 100G transmission over four different wavelengths around 1310nm. It can support distances up to 10km.
QSFP28 ER4 Lite: QSFP28-ER4 Lite is a 100Gbps transceiver designed for optical communication applications compliant to Ethernet 100GBASE-ER4 Lite standard. The high performance cooled LAN WDM EA-DFB transmitters and high sensitivity APD receivers provide superior performance for 100Gigabit Ethernet applications up to 25km links without FEC and 32km links with FEC.

Why Do I Need an OTDR?

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(OTDR) is an optoelectronic instrument used to characterize an optical fiber. An OTDR is the optical equivalent of an electronic time domain reflectometer. It injects a series of optical pulses into the fiber under test and extracts, from the same end of the fiber, light that is scattered (Rayleigh backscatter) or reflected back from points along the fiber. The scattered or reflected light that is gathered back is used to characterize the optical fiber. This is equivalent to the way that an electronic time-domain meter measures reflections caused by changes in the impedance of the cable under test. The strength of the return pulses is measured and integrated as a function of time, and plotted as a function of fiber length.
Fiber testing is essential to provide confidence that the network is optimized to deliver reliable and robust services without fault.
Outside Plants
Telecom, video, and data wireless service providers and network operators want to insure that their investments into fiber networks are protected. In outside fiber optic plant, every cable will be tested for end-to-end loss and with an OTDR to ensure the installation was properly made. Installers will be asked to use loss test sets (source and power meters) as well as OTDRs, performing bi-directional tests and providing accurate cable documentation to certify their work. Later, OTDRs can be used for troubleshooting problems such as break locations due to dig-ups.
Premises, LAN/WAN, Data Centers, Enterprise
Many contractors and network owners question whether they should perform OTDR testing for premises cabling. They also want to know if OTDR testing could replace the traditional loss testing with a power meter and a light source. Premises fiber networks have tight loss budgets and less room for error. Installers should test the overall loss budget with a light source and power meter (Tier 1 certification required by TIA-568C standards). OTDR testing (Tier 2 certification) is a best practice that can pinpoint the causes for excess loss and verify that splices and connections are within appropriate tolerances. It is also the only way to know the exact location of a fault or a break. Testing a fiber link with an OTDR also helps document the system for future verification.

How to Clean and Connecting Optical Fibers to OTDR

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If your fiber optic cable is not properly aligned and/or connected, you will notice heavy loss and reflection. Properly cleaning and connecting optical fibers to OTDR is important, please follow the following steps to clean the fibers and connecting it to OTDR.
To connect the fiber optic cable to the port:
1. Inspect the fiber using a fiber inspection microscope. If the fiber is clean, proceed to connecting it to the port. If the fiber is dirty, clean it as explained below.
2. Clean the fiber ends as follows:
2a. Gently wipe the fiber end with a lint-free swab dipped in isopropyl alcohol.
2b. Use compressed air to dry completely.
2c. Visually inspect the fiber end to ensure its cleanliness.
3. Carefully align the connector and port to prevent the fiber end from touching the outside of the port or rubbing against other surfaces. If your connector features a key, ensure that it is fully fitted into the port’s corresponding notch.
4. Push the connector in so that the fiber-optic cable is firmly in place, thus ensuring adequate contact.
If your connector features a screwsleeve, tighten the connector enough to firmly maintain the fiber in place. Do not overtighten, as this will damage the fiber and the port.
Note:
Always inspect fiber ends and make sure that they are clean as explained below before inserting them into the port. Most OTDR suppliers are not responsible for damage or errors caused by bad fiber cleaning or handling.
Ensure that your fiber optic patch cord has appropriate connectors. Joining mismatched connectors will damage the ferrules.
To keep connectors clean and in good condition, We strongly recommends inspecting them with a fiber inspection probe before connecting them. Failure to do so will result in permanent damage to the connectors and degradation in measurements.

OTDR FAQ, for all kinds of OTDR

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 OTDR is short for Optical Time Domain Reflectormeter, The OTDR act likes RADAR, it injects a series pulse (laser) from the OTDR fiber interface and transmits over the optical fiber and detects the returning signal from the fiber back-scatter and reflecting from joints (including splicing, active connecting, etc), Based on the return signal, the OTDR generates trace and display on the screen. From the trace, the OTDR device is able to calculate fiber length, attenuation and joint loss for the optical fiber.
What is the basic function for the OTDR?
Measure the length for the optical fiber
Measure the optical fiber distance between two sites
Locate fault points and ruptures of the optical fiber
Showing the trace for the optical fiber
Measure the attenuation for the optical fiber cable
Measure the refection of the reflection events for the fiber cable
2>. What’s the basic feature that an OTDR should have?
There is distance, loss and reflection figure for each event
It should display the length and attenuation for the whole fiber cable
Large storage function for traces
Easy operation and with GUI interface.
RS232/USB/Network etc to upload data to a PC
PC analysis software to analyzing the stored data
Generate report for the tested traces
Back light for dark and night operation
Built-in VFL (Visual Fault Locator)
3>. How to select an OTDR?
Before you buy the OTDR, please evaluate your needs and the skill of the intended users first, ask yourself several questions:
Are you installing or maintaining fiber?
If Maintenance, is finding the location of the fault the main task?
If Installation, do you need measure more than loss and length? E.g. Connector quality, dispersion, Optical Return Loss?
If you get the answer, please visit link for more details about choose the right OTDR: How to choose the right OTDR?
4>. How many OTDR manufacturers in the market?
There are many manufactures like EXFO, JDSU, Fluke, FIBER-MART, Yokogawa, Anritsu, etc.
5>. What is the dynamic range
The dynamic range determines the total optical loss that the OTDR can analyze, and the total length of the fiber link can measure unit. The higher the dynamic range, the greater the distance the OTDR can analyze. The specification of the dynamic range must be carefully considered for two reasons as below.
OTDR manufacturers specify the dynamic range of ways (playing with specifications as pulse amplitude, signal-to-noise ratio, averaging time, etc.). It is therefore important to understand them thoroughly and avoid making comparisons unsuitable.
Having an insufficient dynamic range results in an inability to measure the full link length, affecting, in many cases, the precision of the link loss and connector losses and attenuation far end . A good method is to select an OTDR empirical whose dynamic range is 5 to 8dB higher than the maximum loss you will find.
6>. What is Event dead zone and attenuation dead zone
Event Dead Zone: Refers to the minimum necessary for consecutive reflection events can be “solved”, ie differentiated from each other. If a reflective event is within the dead zone event that precedes it, it cannot be detected or measured correctly. Industry standard values ranging from 1-5 m for this specification.
Attenuation Dead Zone: Refers to the minimum required distance after a reflective event, for the OTDR to measure a loss of reflective event or reflection. To measure and characterize small links or locate faults in cables and patch cords, it is best to have the attenuation dead zone as small as possible. Industry standard values ranging from 3 to 10 m for this specification.
7>. What is the pulse, and how to choose pulse width based on the fiber length
The key is to always use the shortest pulse width possible that will satisfy the trace quality and allow the user to see the end of the fiber. Short pulse widths are used for short fibers. Long PW’s are used on long fibers. If the trace quality exhibits excessive noise that cannot be removed by additional averages, select the next higher pulse width.
8>. What is OTDR resolution
The sampling resolution is defined as the minimum distance between two consecutive sampling points acquired by the instrument. This parameter is important because it defines the ultimate distance accuracy and ability OTDR troubleshooting. Depending on the selected pulse amplitude and the range of distance.
9>. Can I use SM OTDR to test MM fiber
It may use SM (Single Mode) OTDR to test MM (Multimode) fiber, but not accurate, the distance, cable loss, connector loss, return loss all may not right, because the laser inject from small core diameter fiber to large core diameter fiber, the laser cannot be fully injected, so the test result is not precise.
10>. What is OTDR Launch Cable, why do I need it.
An OTDR Launch Cable is able to allow the OTDR to measure the loss and reflection of the first connection in the link. However, it won’t eliminate the ‘dead zone’ after the first connection in the fiber link. We generally recommend 1km launch cable for the fiber network.
11>. What is tail cord and why do I need it.
A tail cord is a long distance patch cord connect to the end of the tested fiber link, it creates OTDR back scatter after the final connection in the fiber link under test, to measure the loss and reflection for the last connection in the network
12>. What is an “echo” or “ghost” event on an OTDR trace
An echo occurs when the OTDR receives unwanted multiple reflections. Large reflective events are more likely to cause multiple reflections due to large amounts of energy reflected back to the OTDR. Portions of the energy reflected multiple times result in echoes. These waveform artifacts look like real events; however they seldom have loss associated with them.
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Fujikura 22S cladding alignment fusion splicer

by http://www.fiber-mart.com

AFL has introduced the Fujikura 22S active cladding alignment fusion splicer. With this model’s moveable v-grooves, splicer errors due to dust and other contaminants are virtually eliminated, says the company. Removable sheath clamps allow the use of fiber holders, and the unit’s large monitor provides a crystal clear image, even in bright sunlight.
“Fujikura continues to improve upon fusion splicing technology by incorporating newer features that make splicing easier,” comments Greg Pickeral, product manager for AFL’s fusion splicing systems. “The Fujikura 22S incorporates many of the advanced features of our more expensive models yet retains the quality and reliability they are known for.”
The fully ruggedized Fujikura 22S chassis provides for shock, dust and moisture protection, while the model’s two camera observation system provides for accurate fiber alignment and loss estimation calculations. Additional features include a long-life battery that provides power for up to 200 splice cycles (including the application of the splice sleeve), and an electrode life which has been extended to 5,000 splices, minimizing downtime for replacement and stabilizations. The unit’s transit case and work tray provide multiple options for utilizing workspace.
Ideal for field splicing, the 22S maintains high quality in the most extreme environments. Software updates are available via the Internet allowing users to quickly update their software as new splice programs become available. The Fujikura 22S is also fully compatible with the company’s FUSEConnect line of fusion installable connectors.

Singlemode fiber and multimode fiber different and selection method(2)

The application of fiber optics is being gradually extended from the trunk or the computer room to the desktop and residential users, which means that more and more users who do not understand the characteristics of the fiber have come into contact with the fiber optic system. Therefore, when designing fiber link systems and selecting products, full consideration should be given to the current and future application requirements of the system, use of compatible systems and products, the greatest possible ease of maintenance and management, and adaptation to the ever-changing field conditions and user installation requirements.

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1. Can a fiber optic connector be terminated directly on a 250 μm fiber?  

 

Loose sleeve fiber optic cable contains bare fiber with an outer diameter of 250 μm, which is very small and fragile. It is unable to fix the fiber and is not enough to support the weight of the fiber optic connector and is very insecure. The connector is terminated directly on the fiber optic cable. At a minimum, a 900 μm tight jacket is required to wrap around the 250 μm fiber to protect the fiber and support the connector.

2. Can the FC connector be connected directly to the SC connector?

Yes, this is just a different connection method for two different types of connectors.
If you need to connect them, you must select a mixed adapter and use the FC/SC adapter to connect the FC connector and the SC connector at both ends. This method requires that the connectors should all be flat ground. If you absolutely need to connect APC connectors, you must use a second method to prevent damage.

The second method is to use a hybrid jumper and two connection adapters. Hybrid patch cords use different types of fiber connectors at both ends. These connectors will connect to the place where you need to connect. In this way, you can use a universal adapter to connect the system in the patch panel, but bring the system budget to budget. The increase in the number of connector pairs.

3. The fixed connection of optical fibers includes mechanical optical fiber connection and thermal welding. What are the selection principles for mechanical optical fiber connection and thermal welding?

Mechanical fiber optic connection, commonly known as fiber optic cold connection, refers to an optical fiber connection method in which a single or multi-fiber optical fiber is permanently connected through a simple connection tool and a mechanical connection technology without the need of a thermal fusion bonding machine. In general, mechanical splices should be used in place of thermal fusion when splices are made at a small number of cores dispersed at multiple locations.

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Mechanical fiber optic connection technology is often used in engineering practices such as line repairs and small-scale applications in special occasions. In recent years, with the large-scale deployment of fiber-to-the-desktop and fiber-to-the-home (FTTH), it has been recognized that mechanical fiber optic connection is an important means of fiber optic connection.

For fiber-to-the-desktop and fiber-to-the-home applications with a large number of users and geographically dispersed features, when the scale of the users reaches a certain level, the construction complexity and construction personnel and fusion splicer cannot meet the time requirements for users to open services. Because of the simple operation, short training cycle, and low equipment investment, the mechanical fiber connection method provides the most cost-effective solution for optical fiber connection for large-scale deployment of optical fibers. For example, in the high corridors, narrow spaces, insufficient lighting, inconvenient on-site power and other occasions, mechanical fiber optic connection provides a convenient, practical, fast and high-performance optical fiber continuation means for design, construction and maintenance personnel.

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 4. What is the difference between fiber optic splice enclosure requirements and fiber optic splice closures used in telecom operators’ outdoor lines in fiber-to-the-home systems?

First of all, in the fiber-to-the-home system, it is necessary to reserve the position of the optical splitter installation and termination, accommodation, and protection of the jumper to and from the optical splitter in the joint box according to actual needs. Because the actual situation is that the optical splitter may be located in the cable joint box, optical cable transfer box, wiring box, ODF and other facilities, and in which the optical cable termination and distribution.

Secondly, for residential quarters, the optical fiber cable splice box is installed in a buried manner. Therefore, the optical cable splice box has higher requirements for buried performance.

In addition, in the fiber-to-the-home project, it may be necessary to consider the entry and exit of a large number of small-core optical cables.